1. Field of the Invention
This invention relates to a process for removing phosphorus-containing materials, POx, alendronate and alendronate byproducts from crude process mother liquors in a bisphosphonate synthesis using a CaCl.sub.2 /CaO precipitation/neutralization and filtration procedure.
2. Brief Description of Disclosures in the Art
Alendronate sodium, 4-amino-1-hydroxybutylidene-1-bisphosphonic acid monosodium trihydrate, is a promising new agent for combatting bone resorption in bone diseases including osteoporosis, particularly in post-menopausal women. The compound, utility and method of preparation are described in U.S. Pat. Nos. 4,922,007 and 5,019,651, both assigned to Merck & Co., Inc.
Large scale processes as described in the above patents for producing alendronate sodium generate large volumes of soluble phosphorus-containing materials (PO.sub.x) including sodium salts of phosphates, phosphites and pyrophosphates as waste.
Generally, wastewater treatment processing (WWTP) facilities can handle on a total daily basis of about 1-10 ppm (mg/L) of phosphorus per liter of waste.
However, the alendronate process can generate as much as 500 mg of phosphorus as PO.sub.x per liter of waste per day greatly exceeding the allowable limit in many geographic regions for wastewater processing and discharge of effluent.
One general method for dealing with this problem has involved passing the wastestream to an acclimated sludge culture to biodegrade the waste PO.sub.x and methanesulfonic acid (MSA) materials.
However, this method suffers from the low amount of PO.sub.x /MSA that an activated sludge can process on a daily basis. For example, out of a waste load of 1000 lbs., of biological oxygen demand (BOD) material, the sludge can, generally only handle 5-10 lbs./day of phosphorus as a bacterial food supplement.
What is desired in the art is a process for recovering and non-process reuse of wastewater phosphorus-containing materials, PO.sub.x, in an environmentally safe, efficient and cost-effective manner.